Convert WindowOpenDisposition to an enum class.

android_webview/native/aw_web_contents_delegate.cc

Index: android_webview/native/aw_web_contents_delegate.cc
diff --git a/android_webview/native/aw_web_contents_delegate.cc b/android_webview/native/aw_web_contents_delegate.cc
index 9588586b41954fd8830a0ca5bea50fb1a71da91e..ad7e7e316dc5fcfecd7d02f9783c241281f6eeb7 100644
--- a/android_webview/native/aw_web_contents_delegate.cc
+++ b/android_webview/native/aw_web_contents_delegate.cc
@@ -138,7 +138,7 @@ void AwWebContentsDelegate::AddNewContents(WebContents* source,
                                            bool* was_blocked) {
   JNIEnv* env = AttachCurrentThread();
 
-  bool is_dialog = disposition == NEW_POPUP;
+  bool is_dialog = disposition == WindowOpenDisposition::NEW_POPUP;
   ScopedJavaLocalRef<jobject> java_delegate = GetJavaDelegate(env);
   bool create_popup = false;